SQL SUM hours by week across number of years - sql

Question

I have a table in a SQL database that holds information about the hours worked by employees across a number of years. Each employee can have more than one record for a specific date and each employees start date can be different.
I am trying to sum the weekly hours of each employee based on their first week.
So if the employee started on the 17/04/2018 any hours logged in this week would be considered week 1 for this employee and the following week would be week two etc.
For another employee week one could start in a different day/month/year etc.
My data includes the following fields:
Sequence_ID: relates to an individual employee
Date_European: relates to each date an employee has logged hours with the minimum of this being the first date the employee started in the company
Hours: The amount of hours logged
I also have a year field in the data which is the year of the Date_European column.
The below is what I have attempted but I know it isn't even close to the format I need.
select
Sequence_ID
,DATEPART(week,Date_European) AS Week
,DATEPART(year,Date_European) AS Year
,SUM([Hours]) AS Weekly_Hours
from [AB_DCU_IP_2018].[dbo].[mytable]
group by
Sequence_ID
,DATEPART(week,Date_European)
,DATEPART(year,Date_European)
order by
Sequence_ID
,DATEPART(week,Date_European)
,DATEPART(year,Date_European)
I tried to create the 'Week' field. From the above code it just gives me what week of a particular year a date relates to. I then added the 'Year' column to distinguish between different years, but again this only gives me what particular year that is.
Is there any way to create a 'Week' field in the format I am looking for? (Week of earliest date and surrounding dates would be week 1).
I was attempting to use the rank and partition by function by couldn't get this to work properly.
Any help would be greatly appreciated as I have been searching for a solution for hours.
Thanks in advance.
EDIT:
How to create the initial table
CREATE TABLE mytable(Sequence_ID VARCHAR(6) NOT NULL ,Date_European DATE NOT NULL ,Hours NUMERIC(5,1) NOT NULL);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/05/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/06/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/07/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/08/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/09/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/12/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/13/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/14/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/15/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/16/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/19/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/20/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/21/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/22/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/23/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/26/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/27/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/28/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/29/2016',7.3);
INSERT INTO mytable(Sequence_ID,Date_European,Hours) VALUES ('da6Wrw','09/30/2016',7.3);
What I want as the desired outcome:
| Sequence_ID | Date_European | DATEPART(week,Date_European) | Hours | Desired_OutCome_Week |
| da6Wrw | 05/09/2016 | 37 | 7.3 | 1 |
| da6Wrw | 06/09/2016 | 37 | 7.3 | 1 |
| da6Wrw | 07/09/2016 | 37 | 7.3 | 1 |
| da6Wrw | 08/09/2016 | 37 | 7.3 | 1 |
| da6Wrw | 09/09/2016 | 37 | 7.3 | 1 |
| da6Wrw | 12/09/2016 | 38 | 7.3 | 2 |
| da6Wrw | 13/09/2016 | 38 | 7.3 | 2 |
| da6Wrw | 14/09/2016 | 38 | 7.3 | 2 |
| da6Wrw | 15/09/2016 | 38 | 7.3 | 2 |
| da6Wrw | 16/09/2016 | 38 | 7.3 | 2 |
| da6Wrw | 19/09/2016 | 39 | 7.3 | 3 |
| da6Wrw | 20/09/2016 | 39 | 7.3 | 3 |
| da6Wrw | 21/09/2016 | 39 | 7.3 | 3 |
| da6Wrw | 22/09/2016 | 39 | 7.3 | 3 |
| da6Wrw | 23/09/2016 | 39 | 7.3 | 3 |
| da6Wrw | 26/09/2016 | 40 | 7.3 | 4 |
| da6Wrw | 27/09/2016 | 40 | 7.3 | 4 |
| da6Wrw | 28/09/2016 | 40 | 7.3 | 4 |
| da6Wrw | 29/09/2016 | 40 | 7.3 | 4 |
| da6Wrw | 30/09/2016 | 40 | 7.3 | 4 |

Answer 1

Set DateFirst 1
select
Sequence_ID,
(datediff(day , DQ.WeekStarted, Date_European) / 7 + 1) EmployeeWeekNumber
,SUM([Hours]) AS Weekly_Hours
--into [AB_DCU_IP_2018].[dbo].[Weekly_Work_Hours_Employee]
from [AB_DCU_IP_2018].[dbo].[All_IPower_HR_Assurance_4]
CROSS APPLY (SELECT DATEADD(day, -1 * (datepart(weekday,start_date) % 7), start_date) AS WeekStarted
FROM YourTable
WHERE <condition to get the start_date you need>
) DQ
group by
Sequence_ID,
(datediff(day , DQ.WeekStarted, Date_European) / 7 + 1)
order by
Sequence_ID
,DATEPART(week,Date_European)
,DATEPART(year,Date_European)

Answer 2

Here is another approach using the sample data you posted.
select mt.Sequence_ID
, mt.Date_European
, DATEPART(week, mt.Date_European)
, mt.Hours
, MyRow.GroupNum
from mytable mt
join
(
select WeekNum = DATEPART(week,Date_European)
, GroupNum = ROW_NUMBER() over(order by DATEPART(week,Date_European))
from mytable
group by DATEPART(week,Date_European)
) MyRow on MyRow.WeekNum = DATEPART(week, mt.Date_European)

Answer 3

try this
select *,rn-1 [Employee_week] from (
select *,dense_RANK() over(Partition by Sequence_ID order by iif(weekly_hours=0,0,week) ) [rn] from (
select
Sequence_ID
,DATEPART(week,Date_European) AS Week
,DATEPART(year,Date_European) AS Year
,SUM([Hours]) AS Weekly_Hours
--into [AB_DCU_IP_2018].[dbo].[Weekly_Work_Hours_Employee]
from [AB_DCU_IP_2018].[dbo].[All_IPower_HR_Assurance_4]
group by
Sequence_ID
,DATEPART(week,Date_European)
,DATEPART(year,Date_European)
order by
Sequence_ID
,DATEPART(week,Date_European)
,DATEPART(year,Date_European))a)a
where rn = 2
This'll give you the hours each employee worked on their first week, use rn>2 to get the remaining weeks

Answer 4

I actually found an easier way to calculate the week number of the employee that uses the DENSE_Rank function.
I have included this below incase anyone as similar issues. I have commented out the DATEPART sections as I was only using these columns as a check to ensure it was working correctly:
select
Sequence_ID
,Date_European
--,DATEPART(week,Date_European) AS Week
--,DATEPART(year,Date_European) AS Year
,DENSE_RANK() OVER (PARTITION BY Sequence_ID ORDER BY DATEPART(year,Date_European), DATEPART(week,Date_European) asc) AS EmployeeWeekNumber
,Hours
from [AB_DCU_IP_2018].[dbo].[All_IPower_HR_Assurance_4]
order by
Sequence_ID
,Date_European
--,DATEPART(week,Date_European)
--,DATEPART(year,Date_European)